Thermostat



1955 2 sheets-sheet 1 Jnven ioni 2 2 Www/5%@ 4 H. SANDVOSS Nov. 23, 1937.

THERMOSTAT Filed June 5,

`Nov. 23, 1937.

H. sANDvss THERMOSTAT Filed June 5, '1935 2 Sheets-Sheet 2 yParental Nov. 23, 1937 UNITED *STATES PATENT oli-rica 2,100,037 THERMOSTAT Hermann Sandvoss, Frankfort-on-the-Main, Germany Application June 5,1935, serial No. 25,135v

2 Claims.

the spring bellows into the container holding the` liquid. To overcome this trouble it has been proposed to employ two separate scales, but this arrangement is bothersome and, in practical opleration, causes confusion and wrong adjustments. 1 Y

. Compared with the prior art, the invention substantially consists in the improvement that the rotary motion inuencing the position cf the pointer and carried out by the rotatable regulating member supported by a buer spring is converted into a relative motion of the pointer with respect to the scale by means operating independently of the axial displacements of the regulating member, whichact counter to the buffer spring.

According to one embodiment of the invention, the scale carrier is so connected with the regulating member that while it cooperates in the axial displacements it does not join in the rotary motions thereof, the' rotary motion of the regulating member causing a relative motion of the pointer with respect to the scale carrier.

Another simplified and improved constructional embodiment of the invention provides for a stationary scale carrier and for coupling a connecting member transmitting the rotary motion of the regulating member to the pointer with the regulating member in such a way that it takes part in the rotary motions but not in the axial displacements of the regulating member.

The application of the invention permits, above all, the optional adjustment of the thermostat by the regulating member from lower to higher regulating temperature, and vice versa, independently of the position and tension of the thermostat, the

adjustment being always accurately indicated on4 one and the same scale without regard to the prevailing initial or excess tension.

Two embodiments of the invention are illustrated, by way of example, in the accompanying drawings, in which Figurel is a view, partly in section, of a thermostat with an operating member; Fig. 2, an elevation of the thermostat Shown Germany June 28, 1934 (Cl.v 297-8) in Fig. 1; Fig. 3, a sectionof the top of another form of the invention; Fig. 4, a cross section of the regulating member with a driving surface;

and Fig. 5, an elevation of the upper part of Fig. 3. l Referring to the drawings, I is a tubular container for receiving the expansion liquid and connected with a head 3 by means of the screw socket 2. The upper portion of the container head 3 contains the packed top end of a spring bellows l0 b5 dipping into the container I and having'its lower end tightly shut oi bythe bottom 6. A bellows f rod 1 connected with the bottom' 6 passes freely movable through a bore t of the head 3. The inner space 8 of the container I communicates by l5 the capillary tube 9 linked with the container by the connection Ill with an operating body II whose pin I2 actuates a valve, flap or other suitable means.

In the construction shown in Figs.

part-has a longitudinal slot I4 which isv limited on top by the stop face I6 and below by the stop face I5. ln the regulating casing I3, a regulating l1 and 2 the 20 head 3 carries a regulating casing I3 whose lower member I1 is rotatably and displaceably disposed g5 and provided at its end projecting from the casing I3 with 'a hand wheel I8 or other suitable means. The lower portion of the regulating member I1 has a sleevelike cylindrical recess I9 iitted-with the internal thread 20 which is in en- 30 gagement with the thread 2I of the bellows rod 1, the thread v2l being accommodated in `the recess I9.

The regulating member I1 has a collar 22 which rests on the stop 23 arranged inside the 35 casing` I3 and serving as abutment for the regulating member I'I which is pressed against itl by means of the buifer spring 24. Between the lower end of the buffer spring 24 and the collar 22 a ball bearing 25 is preferably provided to facilitate the 4o turning of the member I'I. The buffer spring 24 is dimensioned so that it will press the collar 22 of the regulating member I'I i'lrmly against the stop 23 and not yield during normal working of the thermostat, but that it becomes compressed 45 in case of overpressure of the expansion liquid due to overheating of the thermostat and permits axial displacement of the bellows rod 1 and the regulating member lII connected ltherewith to prevent damage to the thermostat.

The buffer spring 2llserves the further purpose of lifting the regulating member II if the bellows rod 'I encounters resistance during rotation of the member I1, in which case, besides the rotary motion ofthe member I1, an axial displacement 56 thereof against the action of the builer spring 24 will occur. To render the adjustment by scale andthe reading independent of Athese axial displacements of the regulating member I1 and of the bellows rod 1 connected therewith the scale is disposed on a separate movable carrier which is so connected with the regulating member I1 that it joins in the axial displacements of the latter but not in the rotary motions thereof which, however, are. utilized to efl'ect relative motion of an indicating member with respect to the scale.

Rotation of the scale carrier is preferably prevented by slidingly .guiding it, say, in the slot Il of the regulating casingl3. For bringing about a deiiectionof the pointer relative to the scale it would suiiice, for instance, to screw the carrier, constructed as'described, like a nut to the regulating member I1 and to secure to the latter a mark for indicating on a scale arranged on the carrier and extending parallel to the axis of the .regulating member I1 the axial displacement of `the carrier caused by rotation of the member I1.

In the construction shown, according to the invention, a circular scale 26 is employed which is secured to a caselike carrier 21 and over which moves a pointer 28 rotatably disposed in the carrier 21. 'Ihe carrier 21 is guided in the slot I 4 and arranged on the regulating member I1 so as to be loosely held in radial direction but axially kept between stops. Rotary motionv of the regulating member I1 is transmitted to the pointer 28 by a gear which preferably comprises aworm 29 non-rotatably secured to the member I1 and cooperating with a toothed wheel 30 rotatably disposed on the scale carrier 21. 28 may be directly attached to the toothed wheel shaft 3l or by means of an interposed gearing. The worm 29 may serve also as driver for the scale carrier 21 by being positioned between the stoplike jaws 32, 33 thereof. Below the jaw 33 a special stop ring 3| is secured to the regulating member I1. The pointer 28 can be adjusted relative to its axis by a knob to permit proper setting according to prevailing conditions at the point of installation of the thermostat.

The mode of operation of the thermostat according to Figs. 1 and 2 is as follows:

Assumed that the thermostat opens or closes a regulating valve according to the temperature at the container I by means of the pin I2 extending from the operating body II. The temperature at which the thermostat actuas the pin4 largement of the space 8 for the expansion liquid. v

The operating body II withdraws therefore its pin I2, and the regulating valve is for instance opened. `The temperature at the container I must then rise again to the newly adjusted control temperature while the expansion liquid in the space 8 expands correspondingly. When the newly adjusted control temperature' isl exceeded, the expansion liquid, which now completely lls the space 8 again, exerts pressure through the capillary tube 9 upon the operating body II Vand eiects for instance the closing of the regulating valve. If the temperature drops below the adjusted limit, the valve is opened again.

The worm 29 cooperates in the rotation of the The pointer regulating member I1 and drives the toothed wheel 38 with the pointer 28 which indicates the adjusted higher control temperature on the circular scale 26 while the scale carrier 21 remains inoperative.

If, on the other hand, the thermostat is to be adjusted from a higher to a lower control temperature, the regulating member I1 is turned in opposite direction, whereby the bellows rod 1 is unscrewed and the spring bellows 5 extended. If the regulating valve is opened, the pin I2 of the'operating body II is pressed into its extreme end position and the valve closed. For the time being, the bellows rod 1 cannot be screwed back any farther, because the expansion liquid lls the entire space 8 and prevents expansion of the spring bellows 5. However, during further rotation of the regulating member I1 the latter, against the action of the buffer spring 24, can be axially displaced upwardly, whereby the buier spring 24 is compressed, and the scale carrier 21 moving in the slot I4 as well as the members 28, 29, 30, 3| also join in this displacement motion. The indication of the adjustment brought about by the rotation of the'regulating member I1 is therefore not aiected by this displacement, the indicating device continuing to operate as in inoperative position and adjusting the pointer 28 on the scale 26. It is therefore possible to adjust the thermostat to the new lower control temperature by means of the scale without further ado.

When the temperature at the container I drops, owing to the continual closing of the regulating valve, the expansion liquid contracts and permits the buier spring 24 to depress the regulating member I1 with the bellows rod 1 and the spring bellows 5 until the space 8 has attained the size corresponding to the new regulating temperature. At that moment, the collar 22 of the member I1 is seated on the stop face 23, and the thermostat continues to operate at the new control temperature. The scale carrier 21 again cooperates in this displacement of the regulating member I1 without causing thereby any change in the position of the pointer 28 relative to the scale 28.

Even if the buffer spring 24 acts during overheating of the thermostat and permits yielding bers will be raised and lowered without affecting thereby the position of the pointer, so that the adjustment of the thermostat is always correctly indicated. AsV explained, the position of the pointer 28 will be varied only during rotation of the regulating member I1.

The construction shown in Figs. 3 to 5 is of a still simpler and more compact type. In the drawing, the lower portionof the thermostat is not shown, since it corresponds to the one shown in Fig. 1. The container head 3 into which at 35 the spring bellows 5 is packed carries the attached or screwed on casing 36 containing a rotatable and axially displaceable regulating member 31 whose top end has a stepped and trimmed head 38 `to facilitate the application of a socket wrench. The cylindrical recess 39 of the regulating member 31 is provided with internal thread 40 into which the bellows rod 5 is screwed which is threaded also.

The buffer spring 4I which could be arranged in a manner similar to the one shown in Fig. 1 is preferably xed in the lower part of the casing 36 between the indicating device an'd the lowerI end and interposed ball bearing 43.

' According to Fig. 3j the preferably caselike scale carrier 44 is stationarily arranged by being connected for instance with the casing 36 by a bolt 45. and a special connecting member transmitting the rotary motion of the-regulating member 31 to a pointer is coupled with the member 31 so as to cooperate in the rotary motions but not in the axial displacements .or buifer motions thereof. An arrangement of this kind can be carried out in various ways, for instance by means of a stationary toothed wheel-.and a channellike longitudinal toothing on the regulating member. The connecting member comprises preferably a worm 46 slideably disposed on a driving face 41 of the regulating member 31 and cooperating with a toothed wheel 48 arranged on the stationary scale carrier 44. The toothed wheel 49 may be directly coupled with a pointer 49 moving over a preferably circular scale 50, the toothed wheel 49 and the pointer 49 being both disposed on the shaft 5I.

The driving vface 41 is simply formed by onesided sloping of the round cross section of the regulating member 91, and the inner wall of the perforated worm 49 has a stop face corresponding with the sloping 41.

'I'he worm 48 is held in position by resting on the bearing surface 52 of the regulating casing 99 and, by means of an interposed disc being held by a spring 54 which with its other end is supported by the head l of the scale carrier 44 surrounding the parts mentioned. By means of the y screw ljoints 5l the scale B9 can be secured to the carrier 44 so as to be turnable and selectively pointing in all directions. In this way, the scale I0 can be always adjusted to keep the numbers on the scale upright and thus facilitate reading. The

pointer 49 can be adjusted on its shaft Bl by means of a knob, and it is further possible to rotatably dispose the scale casing 44 on the regulating casing 38.

'Ihe thermostat according to Fig. 3 to 5 functions substantially like the one shown in Figs. 1 and 2. During rotation of the regulating 4member 31 in one or the other direction the bellows rod 1 engages more or less the internal thread 40, whereby the spring bellows I is shortened or extended.' 'I'he worm 46 cooperates in the rotation of the regulating member 31 and, by

means'of the toothed wheel 49, adjusts the pointer 49 so that the amount of lrotation can be read on the scale l0.' *M

When during adjustment from a higher to a lower control temperature the regulating member l1 is axially displaced against the action of after cooling and contraction of the expansion liquid the regulating member '91 is pressed down by the buffer spring 4| until the collar 42 rests on the head 3, the member 31 with its face 41 slides down in the worm 46 without causing a variation in the scale indication, which is effected only by a rotation of the member 31.

The regulating member 31 can in similar mandisplacement, a stop in the casing. spring eperativeiy connected to the regulating member for holding the regulating member against the stop, means for rotating the regulating member, a female thread on the regulating member, a male thread -on the bellows rod engaging in the femaie thread of the regulating member, a carrier secured to the casing. a scale on the carrier, a pointer rotatably mounted on the carrier for cooperation with the scale. mechanism on the carrier for rotating the pointer, a worm gear forming part of the mechanism, a worm meshing with the worm gear and mounted on the regulating member for relative axial displacement with respect to, and for positive tangential engagement with, the regulating member, and checks on the casing arranged to engage opposite sides of the worm for holding it in position with respect tothe worm gear. 4

2. A thermostat comprising a casing, a container for an expanding liquid connected to the casing, a spring bellows in the container, a bel- G lows rod in the spring bellows, a regulating .mem-

ber mounted in the casing for rotation and axial displacement, a stop in the casing, a spring operatively connected to the regulating member for holding the regulating member against the stop, means for rotating the regulating member. a female, thread on the regulating member. a male thread on the bellows rod engaging in the female thread -of the regulating member, a carrier secured to the casing, a scale on the carrier, a pointer rotatably mounted on the carrier for cooperation with the scale,y mechanism on the carrier for rotating the pointer, a worm gear forming part of the mechanism, a worm meshing with the worm gear and mounted on the regulating member for relative axial displacement with respect to, and for positive tangential engagement with, the, regulating member, a ilxed and a movable check arranged on the casing to engage opposite sidesof the worm.

vand a spring operatively connected to the movable check, for holding the worm in position 4with respect to the worm gear. l a

' SANDVOSS.v 

